If you'd like to try out Jest with an existing codebase, there are a number of ways to convert to Jest:

  • If you are using Jasmine, or a Jasmine like API (for example Mocha), Jest should be mostly compatible, which makes it less complicated to migrate to.
  • If you are using AVA, Expect.js (by Automattic), Jasmine, Mocha, proxyquire, Should.js or Tape you can automatically migrate with Jest Codemods (see below).
  • 如果你喜欢 chai，你可以升级Jest并继续使用chai。 However, we recommend trying out Jest's assertions and their failure messages. Jest Codemods can migrate from chai (see below).

jest-codemods

If you are using AVA, Chai, Expect.js (by Automattic), Jasmine, Mocha, proxyquire, Should.js or Tape you can use the third-party jest-codemods to do most of the dirty migration work. It runs a code transformation on your codebase using jscodeshift.

To transform your existing tests, navigate to the project containing the tests and run:

  1. npx jest-codemods

More information can be found at https://github.com/skovhus/jest-codemods.